Wireless Power Transfer Thin Profile Coil Assembly

A resonant induction wireless power transfer coil comprising:

• a 2n-layer coil stack, where n is a positive integer, comprising:
• a dielectric between conductors connected to operate in a differential mode, the dielectric having a first side and a second side,
• the conductors including a first conductor pattern comprising a first plurality of conductors wound in a spiral on the first side of the dielectric to provide a forward current path conductor, and
• the conductors including a second conductor pattern comprising a second plurality of conductors wound in a spiral on the second side of the dielectric to provide a return current path conductor, the second conductor pattern being aligned with the first conductor pattern whereby the second conductor pattern reinforces magnetic flux generated by the first conductor pattern,
• wherein the first and second conductor patterns are placed relative to one another so as to provide flux transmission in a same direction and to provide a designed capacitance across the 2n-layer coil stack;
• and
• at least one of a parallel or a serial electrical connection at one end of conductor patterns between layers of the coil stack,
• wherein designed capacitance is selected such that the 2n-layer coil stack and the designed capacitance together self-resonate at a predetermined wireless power transfer operating frequency fr=1÷(2π√(LC)) that is being used for wireless power transfer with another wireless power coil of a wireless power transfer apparatus, where L=equivalent coil inductance of the 2n-layer coil stack and C=equivalent capacitance of the 2n-layer coil stack.